FIG. 1 is a schematic diagram of a network architecture of an optical access network. The optical access network includes a passive optical access network and an active optical access network. The passive optical access network includes: fiber to the x (FTTx), and the active optical access network includes: a Digital Subscriber Line Access Multiplexer (DSLAM). In the passive optical network, the DSLAM is connected to an Optical Line Terminal (OLT) through the Ethernet. According to a Optical Network Unit (ONU), the FTTX is classified into several situations: Fiber To The Home (FTTH), fiber to Distribution Point (FTTDp), fiber to the Building (FTTB), fiber to the Curb (FTTC), and the like. A Passive Optical Network (PON) technology is mainly used in a fiber access network. In the prior art, a PON mainly has two types: a Gigabit Passive Optical Network (GPON) and an Ethernet Passive Optical Network (EPON). The PON technology is a point-to-multipoint Optical Access Network (OAN) technology. A PON may include an OLT and an ONU, or a PON may include an OLT and an Optical Network Terminal (ONT), or a PON may include an OLT and a Multi-Dwelling Unit (MDU). In the network architecture of the optical access network shown in FIG. 1, an ONU, an ONT, an MDU, or a DSLAM may be collectively referred to as an access device. An OLT may be referred to as a central device. Customer Premises Equipment (CPE) is connected to an Internet Protocol (IP) network by using an access device and a central device.
In the prior art, in an optical access network, a central device (for example, an OLT) or a Dynamic Host Configuration Protocol (DHCP) server needs to configure one public IP address for each access device, such as an ONU, an ONT, an MDU, or a DSLAM, so as to implement that user equipment accesses an IP network by using the access device. In this way, a public IP address needs to be configured for each access device, which results in complex management and difficult maintenance of the access device.